<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    //异步编程
    //需求 1秒后控制台输出111，2秒后222，3秒后333
    //回调地狱
    // setTimeout(() => {
    //   console.log(111)
    //   setTimeout(() => {
    //     console.log(222)
    //     setTimeout(() => {
    //       console.log(333)
    //     },3000)
    //   },2000)
    // },1000)


    function one(){
      setTimeout(() => {
        console.log(111)
        iterator.next()
      },1000)
    }

    function two(){
      setTimeout(() => {
        console.log(222)
        iterator.next()
      },1000)
    }

    function three(){
      setTimeout(() => {
        console.log(333)
        iterator.next()
      },1000)
    }

    function * gen(){
      yield one()
      yield two()
      yield three()
    }
    //调用生成器函数
    let iterator = gen()
    iterator.next()
  </script>
</body>
</html>